Question

If a newly arisen allele is beneficial, do you think this will have an effect on the probability that this allele will get fixed in the population? What if the allele is detrimental? Does drift or selection have a greater effect on the probability of fixation or loss of an allele, and what information would you need in order to determine this?

Answer 1

• Genetic drift deviation form null hypothesis, based on finite population size.
• Due to genetic drift the population size itself may determine genotype and allele frequencies.
• Finite population will result in the variation in the allele frequency, due to random chance.
• In genetic drift, selection of an allele based on "sampling error" and is more effective in smaller population.
• Thus, the fixation of beneficial or deleterious allele will be a chance event and either may be fixed in the population.
• Smaller the population, there is higher chance of genetic fixation of an allele or its reduction.
• Thus, in a small population, there is a chance for a neutral allele to become extinct or increase in frequency, to eventually become fixed.
• Probability that an allele will be fixed in a population = the frequency of the allele in the population.